The present invention relates to antigens and, more particularly, to a synthetic antigen for polychlorinated biphenyls, a method of making same, and an antibody raised by the same.
Polychlorinated biphenyls (PCB) comprise a large group of chemically very stable compounds. They are heat stable, non-volatile and non-biodegradable. Due to these physical properties PCB has been extensively utilized since the 1930's as insulating materials, thermal conductors in electrical equipment, hydraulic oils, and plasticizers in rubber and synthetic resins. PCB has also been used for dust control, as components of newspaper and carbonless copy paper ink, for moisture proofing components of foodpacking materials, for sealing and impregnation, as vapor suppressants and incorporated into insecticides (such as DDT and Dieldrin) to prolong kill life and increase toxicity.
PCB was not produced on a large scale until about 1929. The synthesis of PCB by catalytic chlorination of biphenyl produces a complex mixture of different homologs and isomers. Theoretically 209 different PCB isomers may exist, and available data indicate that approximately 80-90 are present in commercial PCB mixtures. Marine environments or human tissue may contain up to 40-50 PCB isomers. The Monsanto Company, the principal producer of PCB within the United States, markets these compounds under the trade name of Aroclor. The Aroclor mixtures are designated by four digit numbers, the last two digits of which generally define the percentage of chlorine by weight. Thus Aroclor 1254 is a mixture of polychlorinated biphenyl isomers with a total of 54% chlorine. The isomeric composition of Aroclor 1254 is 11% tetrachloro-, 49% pentachloro-, 34% hexachloro-, and 6% heptachlorbipheyl.
PCB is distributed in oceans, fresh water and estuaries. It has mutagenic effects on animals, fish and birds. It is generally taxic in animals and may produce a variety of symptoms including chloracne, porphyria, hematologic alterations, thymic atrophy and lymphatic changes as well as adverse effects on the liver and kidney tissue, gastric mucosa, and menstrual and reproductive cycles. It has a relatively long half-life of about 25 years. In view of the toxicity of PCB and its long half-life, on the one hand, and the complexity of its analytical analysis in aqueous media, on the other, a rapid method for quantifying it is of utmost importance.
Radioimmunoassay (RIA) is a specific, sensitive, precise and economical technique for microdetermination of compounds in aqueous systems. The prior art techniques for assessing compounds, including gas chromotography and mass spectrophotometry, have certain disadvantages not encountered by RIA. On the other hand, RIA requires an antibody. The essence of the immune system is its ability to recognize surface features of macromolecules that are not normal constituents of the organism. Antibodies are protein molecules produced by organism that carry out this specific recognition. The foreign entities that they recognize are called antigens. The portion of the antigen to which an antibody binds is called an antigenic determinant. An immunogen is an antigen that elicits a response from the immune system. Macromolecules such as foreign proteins, nucleic acids, and carbohydrates usually are effective immunogens. Molecules with molecular weights of less than 5000 usually are not. However, low molecular weight compounds not antigenic by themselves (termed haptens) can act as a potent antigenic determinants, if they form a covalent bond with a large carrier macromolecule to form a conjugate. The low molecular weight substance must contain at least one functional group capable of covalently bonding to an available functional group of the carrier. Characteristically strong covalent bonds are required to prevent in vivo lysis or cleavage of the conjugate during the immunization process. Furthermore, neither structural alteration of the low molecular weight substance nor denaturation of the carrier can occur during conjugation if a useful antigen is to be produced. The conjugate must also remain soluble to preserve reactivity.
Accordingly, it is an object of the present invention to provide a synthetic antigen for PCB.
Another object is to provide an antibody raised by such an antigen.
A further object is to provide a method of synthesizing such an antigen.